From: Emily Shaffer <emilyshaffer@google.com>
To: git@vger.kernel.org
Cc: Emily Shaffer <emilyshaffer@google.com>,
Jeff King <peff@peff.net>, Jonathan Nieder <jrnieder@gmail.com>
Subject: [PATCH v4] grep: fail if call could output and name is null
Date: Thu, 23 May 2019 13:23:56 -0700 [thread overview]
Message-ID: <20190523202355.152742-1-emilyshaffer@google.com> (raw)
In-Reply-To: <20190522003402.77767-1-emilyshaffer@google.com>
grep_source(), which performs much of the work for Git's grep library,
allows passing an arbitrary struct grep_source which represents the text
which grep_source() should search to match a pattern in the provided
struct grep_opt. In most callers, the grep_source::name field is set to
an appropriate prefix to print before a colon when a result matches:
README:Git is an Open Source project covered by the GNU General
One caller, grep_buffer(), leaves the grep_source::name field set to
NULL because there isn't enough context to determine an appropriate name
for this kind of output line. In practice, this has been fine: the only
caller of grep_buffer() is "git log --grep", and that caller sets
grep_opt::status_only, which disables output and only checks whether a
match exists. But this is brittle: a future caller can call
grep_buffer() without grep_opt::status_only set, and as soon as it hits
a match, grep_source() will try to print the match and segfault:
(null):Git is an Open Source project covered by the GNU General
For example, a future caller might want to print all matching lines from
commits which match a regex.
Futureproof by diagnosing early a use of the API that could trigger that
condition, before we know whether the pattern matches:
BUG: grep.c:1783: grep call which could print a name requires
grep_source.name be non-NULL
Aborted
This way, the caller's author gets an indication of how to fix the issue
- by providing grep_source::name or setting grep_opt::status_only - and
they are warned of the potential for a segfault unconditionally, rather
than only if there is a match.
Noticed while adding such a call to a tutorial on revision walks.
Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
---
Since v3, only the commit message has changed. Reworked based on
Jonathan Nieder's suggestions (with some modifications for readability).
- Emily
grep.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/grep.c b/grep.c
index 0d50598acd..f7c3a5803e 100644
--- a/grep.c
+++ b/grep.c
@@ -1780,6 +1780,10 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
enum grep_context ctx = GREP_CONTEXT_HEAD;
xdemitconf_t xecfg;
+ if (!opt->status_only && gs->name == NULL)
+ BUG("grep call which could print a name requires "
+ "grep_source.name be non-NULL");
+
if (!opt->output)
opt->output = std_output;
--
2.22.0.rc1.257.g3120a18244-goog
next prev parent reply other threads:[~2019-05-23 20:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-16 2:00 [RFC PATCH] grep: provide sane default to grep_source struct Emily Shaffer
2019-05-16 3:07 ` Junio C Hamano
2019-05-16 3:13 ` Jonathan Nieder
2019-05-16 3:11 ` Jonathan Nieder
2019-05-16 21:05 ` Emily Shaffer
2019-05-16 21:44 ` [PATCH v2] " Emily Shaffer
2019-05-16 22:02 ` Jeff King
2019-05-21 23:52 ` Emily Shaffer
2019-05-22 0:17 ` Jonathan Nieder
2019-05-22 0:34 ` [PATCH v3] " Emily Shaffer
2019-05-22 0:58 ` Jonathan Nieder
2019-05-22 4:01 ` Jeff King
2019-05-23 20:23 ` Emily Shaffer [this message]
2019-05-23 20:34 ` [PATCH v4] grep: fail if call could output and name is null Jonathan Nieder
2019-05-28 17:57 ` Junio C Hamano
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190523202355.152742-1-emilyshaffer@google.com \
--to=emilyshaffer@google.com \
--cc=git@vger.kernel.org \
--cc=jrnieder@gmail.com \
--cc=peff@peff.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).